<?xml version="1.0"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="BOOKS">
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" name="BOOK">
          <xs:complexType>
            <xs:sequence>
              <xs:element minOccurs="0" name="title" type="xs:string" />
              <xs:element minOccurs="0" name="subject" type="xs:string" />
              <xs:element minOccurs="0" name="isbn" type="xs:unsignedInt" />
              <xs:element minOccurs="0" name="author">
                <xs:complexType>
                  <xs:attribute name="city" type="xs:string" use="optional" />
                  <xs:attribute name="name" type="xs:string" use="optional" />
                  <xs:attribute name="gender" type="xs:string" use="optional" />
                  <xs:attribute name="email" type="xs:string" use="optional" />
                </xs:complexType>
              </xs:element>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>